A leading manufacturer of garden tools reports its biggest selling item is the garden rake. The traditional garden rakes are designed for raking lawns to remove grass clippings, twigs and leaves. To minimize digging into the soil, the tines are flexible wires or strips of metal, bamboo and plastic, the ends contoured to cradle the raked objects as the rakes are stroked back and forth. The old fashion rakes with rigid wooden spokes or steel spikes are relegated to smoothing the surfaces of earth in garden areas. These are unsuitable for lawns or cut grass.
Rakes with flexible steel tines, a network of wires or steel strips have replaced rakes with shaped bamboo pieces largely because these provide longer service, and cause less damage when raking tender shoots. Rakes made of plastic are popular because they are low in cost by being pressed or molded in one piece. The design of rakes as a whole has been simply to accommodate the action of the tines. The rest of the rake is merely support for the tines.
Manufacturers of plastic rakes have directed their attention to making rakes with elements of tougher plastic. Thus, a wide assortment of plastic rakes are available. The emphasis on applying the new technologies, which are built around plastic materials, are well known. Very little thought appears to have been focused on making a more efficient rake; that is on making the tines do their job more efficiently. An example of one place where a more efficient rake is needed is where one is required to rake off small materials, particularly gravel or cut stone, from a grassy lawn. The presently designed rakes are inefficient in trapping and moving these small objects forward.
Anyone who has had a great deal of experience when confronted with the job of raking small objects has developed strategies to make the raking job better. One way is to change the angle of the stroke from directly back and forth to raking at an oblique angle. This alternative, of angling the tines, causes the apparent gap between the tines to be decreased. Therefore, by operating in this manner, fewer strokes are needed to dig out and move small objects resting on grass. This pattern of raking is useful when a few objects necessitate removal.
It is clear that there is a relationship between the efficiency of movement of the objects being raked and the energy necessary to move the rake through each sweeping cycle. The rake performs its function because of the resiliency of the tines. That is, the sweeping motion of the rake along the ground causes the tines to be bent, by the resistance of the ground, away from the direction of sweeping. As the end of each sweep is reached, and the rake is somewhat lifted from the ground, the resistance of the tines is slackened, and the tines spring back to their normal position. This springing action is the most important component in moving the material being raked in the direction of sweeping.
It will also be clear that, as the tines spring forward, some of the material being swept will pass laterally off the tines, will move into the space between the tines, and will therefore not be subjected to the springing action of the tines. Therefore these pieces of material will not be swept forward. If more tines are included in the same width of rake, or if wider tines are provided, there will be less space between the tines, and the sweeping efficiency will necessarily be greater.
However, if the tines are made wider, they will be less flexible, which will make for lower sweeping efficiency. From this point of view, the ultimate rake is therefore a hoe, which has a single "tine" over its entire width. It will be clear that a hoe is not an efficient tool for the raking of small objects, such as pebbles or grass clippings, from a lawn or the like.
In either case, within a given width of rake, it is known that there is a best balance between the width of the individual tines, the number of tines, and the spacing of the tines which will give the most efficient raking for a given amount of input raking energy. Manufacturers of rakes which are commercially available more or less recognize these parameters.
In many popular versions of rake design, the rakes are equipped with one of two configurations of extended tines. In one design, a number of tines, wires, or strands are bonded together at one end, and the opposite ends are extended fan-shape. The open spaces between the extremities of the bound pieces are anchored by straps or rods. These are usually placed below the point where the end pieces are bunched or bundled together and joined to a suitable handle. The open spaces at the extremities of the tines often vary from about 1 to 11/2 inches.
Another arrangement, which often finds application along with the use of steel tines or strips, is to extend all of these tines generally parallel from a single header. In this manner, as many as 24 tines can be attached to 20" header. The tines may be about 10 inches long, and the extremities anchored by a cross-strap to maintain end spacings of about 1 inch. The assembly, or header and the attached tines, is held in a fixed position by straps extending from the header to the yoke where the rake handle is installed.
In any of the usual configurations of rakes, the tines may be relatively straight or may have their ends curved so as to point in the general direction in which it is intended for the rake to move the small materials being raked. The angle of the curved ends makes for greater efficiency in springing the material being raked forward, but, of course has the detriment that it takes more energy on the part of the user to bend the curved tine tip than it would to bend a flat tine tip.
Persons with raking experience recognize the essential differences between a rake with a fan shaped tine assembly, and one where the tines (sometimes about 10 inches in length) extend generally parallel from a single unitized header. Between these two extreme shapes, are some fan shaped units molded of plastic, and others molded as to cause the tines to extend in a generally parallel configuration from a single header or manifold.